I don't have Photoshop. Could you attach:
A .msh exported from Photoshop
Dimensions of the image it was created for
Before and after image of the mesh's distortion
Then I can take a look... no promises

Update!
New: saving a preset includes all settings in the dialog
Fix ArgumentOutOfRangeException when getting too wild with the gradient handles
Fix crash on loading a bad file
Fix transparent color if nodes overlap
Fix: Default preset would sometimes remember changes made while it was active
Fix crash if spread or reverse functions are used with 1 or 0 colors
Installer:
New: now supports installing plugins for Window Store version of paint.net
New: add option to start paint.net after successful installation

Update!
Grid Warp:
New: feature to choose gridline color
Fix crash when opening colors page if clipboard image is smaller than preview
Fix crash when there's an error saving or loading gridwarp files
Fix: alpha turns to 0 if a color chooser starts at black and a slider is used
Gradient Mapping:
New: saving a preset includes all settings in the dialog
Fix ArgumentOutOfRangeException when getting too wild with the gradient handles
Fix crash on loading a bad file
Fix transparent color if nodes overlap
Fix: Default preset would sometimes remember changes made while it was active
Fix crash if spread or reverse functions are used with 1 or 0 colors
Installer:
New: now supports installing plugins for Window Store version of paint.net
New: add option to start paint.net after successful installation

This should be fixed in the beta attached below. Please give it a try.
It was caused if there was an image on the system clipboard smaller than the clipboard preview in the context menu. (16x16 then, 33x33 now)
This is implemented in the beta attached. Just click the new Color wheel button on the left side. Note that this also replaces the right-click menu for the background and frame color settings.
<deleted attachment - please get the release version from the pack thread>